It is the kind of agony no parent should ever have to endure: The shocking death of their newborn son and twisted injury to his six-week-old twin brother – allegedly at the hands of a 'trusted' PhD student friend, according to prosecutors.

Faced with that reality, a grief-stricken Ethan Katz, 31, and wife Savannah Roberts, 32, have spent the past two years trying to quietly rebuild their lives in Pennsylvania as they strive for a sense of normalcy for their surviving child.

Now, exclusive Daily Mail photos show the parents and their two-year-old boy, Ari, adapting to their new so-called normality in Pittsburgh – as their other son's accused killer, Nicole Virzi, pleaded guilty in court Wednesday

Virzi, the 32-year-old daughter of a top New York cardiologist who was weeks away from earning her PhD in clinical psychology, had been facing a possible death sentence if convicted for the alleged June 2024 attack on her best friend's twins – Leon and Ari – while babysitting them.

Leon died after suffering fatal head injuries, while his brother sustained wounds to his genitals.

Virzi appeared in court Wednesday and pleaded guilty to third-degree criminal homicide, as well as aggravated assault and endangering the welfare of children, after accepting a plea deal on a total of six counts. She will be ordered to serve between 35 and 80 years in state prison.

Virzi entered the courtroom in full shackles, wearing a lime green prison jumpsuit with her hair in a ponytail, and showed little emotion.

Savannah, meanwhile, gave a wrenching impact statement in which she said, in part: 'Nicole’s actions have completely changed me as a person. I’ve learned that the bogeyman is real and monsters really do live under the bed.'

While Virzi has been languishing in jail ever since her arrest, the Katzes have been quietly trying to adapt.

Savannah told the courtroom Wednesday that it is almost impossible for her to go into a bathroom because of the way Leon’s head was smashed into the tile of the family’s bathroom. 

She added that her husband has to stand outside the bathroom holding their surviving son, Ari, while she’s inside. 'I wince whenever I have to step on a tile floor,' she said.

Apparently too grief-stricken to remain in the rented apartment where Virzi allegedly attacked their precious boys, the couple left Pittsburgh's hip Shadyside neighborhood to a family-friendly area close to several parks and Carnegie Mellon University.

There, Savannah, an award-winning researcher, is within easy reach of the University of Pittsburgh, where she is currently completing her PhD in clinical and developmental psychology and a predoctoral internship in clinical psychology at a psychiatric hospital.

It is unclear what Ethan does for a living. He spent a couple of days inside the couple's home, emerging to go for a walk and take Ari in his stroller to and from pre-school.

The Katzes have enrolled Ari into a pre-school close to their new home, a townhouse-style apartment nestled in a quiet residential complex.

The family were recently seen enjoying rare moments of normalcy last month, including hosting a group playdate and spending time with friends who appear to have rallied around them in the wake of their heartbreak.

Little Ari and his parents already seem to be popular members of their preschool community.

Last month, the family hosted a sunset playdate in their communal garden for several kids and their parents, complete with pizza and a child-sized basketball hoop.

Savannah appeared every bit the doting mom the next day as she and Ari spent several blissful hours in a playground before admiring the colorful arts and crafts stalls at a family reading festival inside the park.

On their return home, Savannah and Ari were joined by Ethan.

In a touching display of their devotion, Ethan and Savannah were seen wrapping their arms around each other as they gazed lovingly at Ari before scooping him up between them as they chatted animatedly to a friend.

At Wednesday's hearing, Savannah gave a wrenching impact statement, alongside her father, David Roberts, and a family friend who gave a statement on behalf of Savannah’s mother, Shelly.

The bereaved mom cried on the witness stand as she recalled the night Leon died and what her life has been like since.

'I'm a twin, my husband is a twin, and it was always our dream to have twins. We thought our dream had come true,' she said.

'[This has] eradicated my sense of safety across every domain of my life. I will never fully understand the torture and murder that Nicole inflicted on my twins.'

As for Virzi's prior confession – in which she told authorities that from a 'very young age,' she had an almost uncontrollable 'urge…to hurt kids' and that 'something just came over me I couldn't control' and 'I did not want him to die' – Savannah said:

'Nicole had a chance to deal with her depravity. But I think she's just telling herself lies to justify her actions.'

The Katzes had politely declined to discuss the then-pending trial, little Leon or how their family was now doing, when approached at their home by a Daily Mail reporter last month. 

But Roberts's mother, Shelly Roberts, who lives in Montana, appeared to be especially proud of her daughter's resilience in the face of the unimaginable tragedy, telling the Daily Mail that Savannah is 'a rock star' and 'an incredible human being.'

The Katzes' rare snatches of peace came before they were set to be reminded of the harrowing ordeal if Virzi went on trial. Through her attorney, Virzi declined to speak in the courtroom Wednesday – but she has written the family of her victims a letter that will be given to them.

The disturbing case began after Virzi, then 29, was repeatedly entrusted with babysitting the six-and-a-half-week-old tots at their family's home.

Savannah and Virzi became close friends while working as research coordinators in the graduate psychology department at Philadelphia's Drexel University.

Virzi, who was raised in the well-heeled suburb of Upper Saddle River, New Jersey, took a week-long vacation from her PhD studies at UC-San Diego, California, to travel to Pittsburgh to meet her friend's sweet baby boys for the first time.

But what should have been a joyful visit soon descended into a living nightmare.

On June 15, the couple rushed Ari to hospital after Virzi claimed she found wounds to his genitals and blood in his diaper, injuries she claimed were caused by him scratching himself on his car seat.

The Katzes rushed Ari to hospital at 6.30pm, where he was found to have swelling, bruising and scratches to his penis, leaving Leon alone with Virzi at the family's apartment, according to a police criminal complaint.

There, Virzi later called 911, telling cops she had fallen asleep to find the infant had fallen from his bouncer seat and hit his head, rendering him unconscious, per the complaint.

Little Leon was later rushed to hospital, where he was pronounced dead from a skull fracture and multiple brain bleeds in the early hours of June 16 – Ethan's first Father's Day and the Katzes' wedding anniversary.

An autopsy later concluded Leon's catastrophic injuries were caused by blunt force trauma and were consistent with child abuse.

Virzi later returned to her nearby Airbnb where she was picked up by police the following day.

She initially denied harming Leon or Ari but later made a shocking video-taped admission to police, revealing she was 'angry' at having to do 'nanny work' during her weeklong vacation.

She told cops: 'So, when I was alone with (Leon) I shook him a couple times - hard. And I dropped him a couple times - hard.'

Virzi said she 'heard some kind of crack' and flipped the infant upside down on the tiled bathroom floor.

'Something just came over me I couldn't control,' Virzi said. 'I'm telling you this because I can't keep lying about it.

'I did not want him to die,' she added. 'That was not my goal. I just wanted him to feel a little pain.'

In the chilling confession, Virzi later told how, from a 'very young age,' she had an almost uncontrollable 'urge…to hurt kids'.

She recounted how, at just seven years old, she once locked a two-year-old child in a bathroom and pinched her until she cried.

In another incident, Virzi said she once placed a hot mug on a baby's arm and pinched them.

'This is the first time this happened as an adult,' Virzi said in relation to the Katz twins.

'There's some weird drive in me that wants to see kids in pain.'

But Virzi had claimed she was bullied into making the 'involuntary' confession during a 13-hour interrogation.

During the interrogation, she claimed, she was shackled to the floor, refused a phone call and forced to pee in front of two police escorts.

Her lawyers unsuccessfully sought to have the confession suppressed, telling a judge investigators 'used every trick in the book to manipulate' her into falsely confessing to causing Leon's death.

But Allegheny County Court of Common Pleas judge Jill Rangos ruled in February the jury should be shown Virzi's confession, observing her statements were 'knowingly, intelligently and voluntarily made.'

Virzi had previously denied harming Leon or Ari. If she had maintained her not-guilty plea, she could have faced trial on charges for which prosecutors would have sought the death penalty.

There is currently a moratorium on executions in Pennsylvania, with the current Democrat governor refusing to sign off on the death warrants. The last execution in the Keystone State was in 1999. 

But, before Virzi's plea deal, the District Attorney's office had insisted the death penalty was appropriate for her given the aggravating aspects of her alleged crimes, including the young age of the victim and evidence he had been tortured.

Bill Difenderfer, one of Virzi's two criminal defense attorneys, previously told the Daily Mail 'negotiations are ongoing' when asked about whether a plea deal might happen.

'This is a very, very serious case. She's still in jail. She still has the support of her family.'

The Daily Mail has reached out to Difenderfer and Virzi's other attorney, Tina Miller, for further comment.

Former colleagues and friends previously told the Daily Mail how Virzi harbored an 'underlying anger' and a 'bottled-up rage.'

Elin Lantz Lesser, who was a grad student at Drexel with Virzi and Roberts, said of Virzi: 'I did always have an instinct of... maybe I need to mind my p's and q's around her a little bit, like I don't want to get on her bad side.'

'But I don't know why because she never did anything negative to me.'

Another former psychology major, who knew Virzi from her studies at a different university, said she was always wary of Virzi.

'There always seemed to be some underlying anger. Some colleagues that I've spoken to have had similar thoughts about it, that there was this bottled-up rage or something that never came out but you felt it was right there, even though she was friendly.'

Virzi's father, Dr Peter Virzi, 70, who remains in Upper Saddle River, refused to comment when approached by the Daily Mail last month. 

He was in the courtroom Wednesday, as was Virzi's mother, Jennifer Graham, 62, who is divorced from Peter and lives in Nyack, New York.

She declined to comment when asked.